Tag Archives: Blue Nebula

Minor Update to BN Librarian

I’ve noticed that a few people, myself included ;-), sometimes forget that, when uploading  new DSP code, the Blue Nebula must be powered from the 12V DC supply input. If you only have the USB cable attached it will appear to work but in fact the new code will not have been uploaded – only the effect names will have changed.

(Technical note: this is because the USB cable only powers the microcontroller and the LCD in the Blue Nebula but the memory chips require 12V from the DC input jack).

To try to avoid this confusion, I’ve added a reminder message that will pop up when you click the Upload DSP button:

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Once you click OK the usual file selector dialog box will open and you can proceed as normal.

This Version of the BN Librarian is 4.04 and, as always, you can download it from the ‘Latest Updates Here’ link at the top of this page.

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Librarian Update to 4.01

Reminder: You need to have Java installed on your computer to be able to run the Librarian. If you have the 32-bit version of Java you will only be able to run the 32-bit Librarian even if your OS is 64-bit. If you have a 64-bit Windows Operating System, please check this page for information on which version of Java you should download if you don’t already have it.

Librarian Version 4.01 is an update that fixes a bug in the previous Version 4.00.

The bug prevented the Librarian from correctly interpreting the ‘Heads’ data sent by the Blue Nebula for emulations with numbers between 5 and 15 that use the ‘coded’ ‘A’, ‘B’, ‘C’, ‘E’ and ‘F’ values. It caused the wrong head letter to be received by the Librarian and all head settings became ‘A’ instead of the correct letter value from the Blue Nebula patch. This incorrect value would have been saved in any patch files saved with the Save Patches button in the Librarian. If this patch data was subsequently sent back to the Blue Nebula using the Send All Patches button it will have corrupted the heads value in the Blue Nebula’s patches. You should check and correct the Heads settings in any affected patches and resend them to the Blue Nebula.

The Blue Nebula Firmware 3.02 does not require a fix for this bug, only the Librarian.

The updated software can be downloaded from the Latest Updates Here link above.

Make sure you download the correct version depending on your Windows Operating System: 32-bit or 64-bit. The 32-bit Librarian will work on 64-bit Windows systems but the 64-bit version of Librarian will not work on a 32-bit Windows OS.

The update for Mac OSX will be available as soon as possible.

 

The Long and Winding Road

Part the Third

“You certainly usually find something, if you look, but it is not always quite the something you were after.”
J.R.R. Tolkien, The Hobbit

In this the penultimate part of the journey the path forks and I take a look at some experiments with using a valve preamp and improvements to the original FET preamp.

Opening the Valves

Eric Thacker, better known as Ecca, had demonstrated on the Shadows Music forum that Piet’s FET and op-amp preamp design could be replaced with a valve (tube) preamp that was available from a number of eBay sellers in Hong Kong and China. (Here, for example).

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The valve preamp and Eccamatic pcb mounted in an enclosure.

The circuit was originally designed to be used as a Hi-Fi stereo preamp using two 6N3 dual triode valves, one valve for each stereo channel. For the eTap2HW module we only require a mono audio pathway so the left channel of the stereo pair was used as the input preamp feeding the echo module and the right channel became the recovery amp, taking the echo module output and acting as a buffer and output level control.

Eric had produced a PCB for his ‘Eccamatic’ design which allowed the echo module to be plugged in, provided a step-up power supply to generate the HT voltage and the LT heater supply for the valves and had connections for the three pots that adjust the echo settings.

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The bits for Eric Thacker’s Eccamatic pcb.

Having already designed the automation circuitry it was easy to adapt the design so that the Arduino Uno would feed the pot inputs on the Eccamatic board, reading the required settings from pots mounted on the front panel.

The front panel also had input and output pots, controlling the signal levels.

I have described this valve EchoTapper build in a series of earlier posts and if you’d like more details just click on the Valve entry in the Categories list on the right of this page.

When the new unit had been completed, the sound was quite pleasing with less hiss and noise than the FET preamp but rather ‘sterile’ as might have been expected from it’s origins as a Hi-Fi design. As I am sure you will know, guitar amplifiers and the early Meazzi echo units have circuits that are far from Hi-Fi for a very good reason (at least in the case of the typical valve-based guitar amp) – the almost perfectly flat frequency response of a Hi-Fi design and it’s deliberate lack of harmonic distortion (achieved largely through the use of negative feedback) is really not what guitarists want or indeed need to get the sound they desire. The original Meazzi preamp is hardly a classic of valve design but somehow has that magic sound that we have come to love.

Piet’s FET preamp design had made use of the ‘Fetzer Valve’ circuit which uses an FET to emulate the sound of a triode valve so it does create harmonically rich sound when the input level control is set correctly to match the guitar pickup level to ‘push’ the Fetzer ‘valve’ into generating the pleasant sounding harmonics we all like.

Steve Mitchell soon had his thinking cap on and he came up with a number of modifications to the valve circuitry that, according to his simulations of the circuit which he had made using the TINA SPICE modeller, should tailor the frequency response better to the typical guitar pickup signal and also generate those desirable harmonics to give that rich sound we all love.

Steve and I came up with a three stage process that culminated in a final design that sounded great.

Stage 1: Remove the built-in stereo volume control pot and increase the input impedance

Stage 1 was essential to allow the input and output level controls to be separated and to provide a better match to the typical guitar pickup’s high impedance.

Stage 2: Remove the negative feedback from the preamp and add Meazzi-like tone shaping

Stage 2 was regarded as highly recommended to obtain a better tone and more gain which would encourage the desirable valve harmonics and tailor the frequency response which was very flat and resulted in a ‘lifeless’ sound, thus improving the sound for guitar purposes.

Stage 3: Add a separate Gain pot and three-way tone switching

The Stage 1 and Stage 2 modifications had resulted in a really good sounding preamp but Steve came up with Stage 3 which would take the whole thing to another level. Whilst not regarded as essential, these mods did make the unit even more flexible. There would now be three ‘level’ controls, the new Gain pot controlling the drive to the second valve stage in the left channel of the amp. The Volume pot controls the signal to the echo module and the Master pot controls the level from the output socket.

Modified Vavle Preamp Flowchart

Flowchart by Steve Mitchell (SCM)

Modified Valve Preamp Freq Responset

Predicted frequency response of the modified circuit

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Front Panel of the final Valve-based Echotapper

The 3-way tone switch provided ‘normal’, ‘vintage’ and ‘warm’ options by tailoring the bass roll-off. On the unit in the picture (built for Mario Voltolini in Italy) I also added, at his request, a Cutting Edge Filter (CEF) which could be switched in and out if required.

Biting the Bulletins

In parallel with the improvements to the valve preamp, Steve was also working on a series of modifications to Piet’s FET preamp design.

One of the problems with any FET is that individual devices, even from the same batch, can have parameters that vary over quite a wide range and this makes it difficult to design a circuit that will allow the FET to operate in the optimum part of its characteristics.

Steve and Rolf Holmberg collaborated and came up with a spreadsheet that would calculate the best resistor values to bias the FET into the optimum operating point. This would be a bit complex for the average user to get to grips with so Steve and I came up with a simpler ‘flowchart’ approach. This would allow the best operating point for the FET to be found using a simple voltage measurement and a little trial an error with a few preferred resistor values.

Steve put together a series of ‘bulletins’ that were published on Piet’s EchoTapper blog which also included simple modifications to improve positive signal headroom, improving the FET gain and reducing white noise (hiss). These mostly involved removing or changing some resistor values and adding some extra capacitors.

Piet has since modified his original preamp PCB design to accommodate these improvements and this is documented on his blog.

What Next?

Now I had two excellent sounding echo units but I had an urge to see if it would be possible to squeeze all this technology into a smaller package, one that would fit on a pedal board or sit neatly on the floor at my feet like a typical guitar effects pedal.

Thus began the germ of an idea that would result in the Blue Nebula. It had to be compact, so that ruled out the use of valves and it needed to be much easier to build, with minimal off-board wiring so that, hopefully, anyone with sufficient experience would be able to put one together from a kit or buy a completed built-to-order unit at reasonable cost.

We had to go from this …

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My first automated eTap2hw

 

to this …

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The final Blue Nebula Design

 

To be continued.

Blue Nebula Librarian Available for Mac OSX

Hi friends and followers. I know you’ve all been waiting patiently for Part 3 of the ‘Unexpected Journey’ but I’ve been away for a break in beautiful Alcudia in Majorca to recharge my personal batteries.

Part 3 is coming shortly but in the meantime I finally got my hands on a Mac thanks to my good friend David Jamieson and have been able to get the Librarian working on OSX El Capitan Version 10.11.4. It should work with OSX 10.9 or above.

If you don’t already have it installed, you will need to install the Java Runtime Environment (JRE), Version 8 or above. To install this go to the Oracle website here and choose the Mac OS X version. I chose the .dmg one and the latest version “Java SE Runtime Environment 8u92” and it installed without any problems.

Screen Shot 2016-04-29 at 20.48.23

You will need to download and install the CH340 driver as this is required to be able to connect via USB to the Blue Nebula and I found that the version on this website worked fine. Once you have downloaded the driver zip file double-click on “CH34x_Install.pkg” to install the driver. You may find that your Mac won’t allow the installer to run as ‘Gatekeeper’ requires apps to be signed so if your Mac won’t install it then do the following:

Go to System Preferences > Security & Privacy > General and click on the padlock at the bottom of the dialog box to enable changes. Under Allow apps downloaded from choose the “Anywhere” option. Close the dialog and the CH340 driver should now install when you double-click the “CH34x_Install.pkg” file. Important: Restart your Mac to activate the new driver.

Run the BN Librarian app by double-clicking it and, if you have a Blue Nebula connected to a USB port on your Mac, when you click on the Serial Port dropdown you should see an entry similar to what I’ve shown in the screenshot above: /dev/cu.wchusbserial* where * will be a number (1440 in the illustration) but this may differ on your computer.

That’s the serial port where your Blue Nebula is connected so click on it to get the Mac and Blue Nebula to start talking to each other. The Blue Nebula resets as usual and after a few seconds it will be ready to communicate with the Librarian running on the Mac.

The Mac OS X and Windows versions of the Blue Nebula Librarian can be downloaded from ‘Latest Updates Here’ on the menu bar above.

 

An Unexpected Journey

“Go back?” he thought. “No good at all! Go sideways? Impossible! Go forward? Only thing to do! On we go!”
J.R.R. Tolkien, The Hobbit

Chapter One

Back in February 2013 (is it really over three years ago?) I started this blog with the idea of documenting a little project that I  had been working on since the previous November.

Little did I know, like Bilbo Baggins in “The Hobbit”, where my ‘unexpected journey’ would lead. In the next few posts I’m going to recount how this …

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November 2012: The First Prototype. It won’t win any prizes for good looks!

ended up with this …

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March 2016: The Blue Nebula

I’d been using a Zoom RFX2000 with the EFTP patches for a couple of years but my ears pricked up back in November 2012 when I heard a couple of demos by Dave Robinson of a new (to me) echo circuit called the eTap2hw which had been designed by Piet Verbruggen.

I couldn’t find anywhere to get a kit to try it our for myself so I posted a question on the ShadowMusic forum and discovered that the kit could be bought from Newtone in Piet’s homeland of the Netherlands. Even then I had to email the guys at Newtone to find out the price and order details.

I managed to order a kit and it went together without any problems thanks to the very detailed instructions Piet had provided on his Echotapper blog and it worked first time. I’d had a lot of experience since I was a young ‘un of building and designing electronics so that probably helped so before November 2012 was out I had a working prototype that, while not pretty (I’d built it in a die-cast box from an old project lying in my garage), it sounded just wonderful. Not only were the echo timings apparently spot on for the various vintage echo machines it was emulating but the unit had a nice warm sound that belied the digital signal processing that lay behind those emulations.

Having heard my prototype in action at the Northern Ireland Shadows Club, my good friend and el-president of the Club, Des McNeill, also started raving (nothing unusual there) about how good and ‘analog’ the eTap2hw sounded so we ended up buying another three kits, two for Des to build and another one for me. What had we started here!

It was now time to produce a proper housing for the eTap2hw’s we were building and Des’ skill as an aero modeller came to the fore here. Des and I worked out a design for the front and rear panels which he then had made up by a company in Belfast. By the time of our next Club meeting Des had his new enclosure built and the first kit assembled and ready to try out and it looked and sounded great.

The boxes Des designed and made (remember I said he was an aero modeller) were constructed beautifully from precision cut plywood, lined on the inside with aluminium foil for screening and covered on the outside with a lovely beige tolex.

These proved so popular with the Club members that Des ended up building five or six more of them and they are still in use regularly on Club days and by the guys who play gigs.

While I was delighted with the sound of my eTap2hw there was one thing I thought it needed to make it even better: a way to store the settings for individual tunes – mainly because I kept forgetting which echo to use for a given tune – TMB syndrome (too many birthdays!).

Thus began the next stage of the journey – automation, as will be revealed in Chapter Two.

 

New Effects Pedal Launching Soon

As some of you will have heard on social media and various forums a new guitar effects pedal to be called the Blue Nebula will be launching soon. The Blue Nebula is a compact stomp-box style effects pedal design with a strong emphasis on accurately emulating the sounds of vintage tape-based echo units but with the ability for users to upload new effects that cover a wide range of other popular sounds.IMG_3108Designed by a four-man team including yours truly (firmware and software), Steve Mitchell (new analog preamp design), Piet Verbruggen (DSP programming) and Mick Taylor (hardware and PCB design), the Blue Nebula is released as an open source/open hardware project.

The Blue Nebula will be available as a kit or built-to-order. Prices to be confirmed.

Main Features

  • Accurately emulates many classic tape echo machines
  • Can be loaded with up to 8 additional general guitar effects such as chorus, phaser, reverbs, shimmer verb and other echo effects which can be uploaded via USB
  • Other effects in the pipeline include emulations of the classic Binson Echorec (think Pink Floyd) and an enhanced Vox Long Tom echo.
  • Three parameter control knobs which, for example, can control dry/wet mix, feedback or chorus rate.
  • Built-in USB and MIDI In ports
  • All firmware updates and new effect sets are uploaded via a normal USB cable – no need for additional special ‘programmers’.
  • Advanced built-in automation firmware controls the Blue Nebula and provides full editing facilities
  • Firmware easily updated via the USB port
  • 16×2 Character LCD display shows patch names, parameter knob functions and other details when editing
  • 22 built-in factory presets for classic Shadows tunes such as Apache, Wonderful Land etc.
  • 128 User definable patches to store any other settings you can come up with
  • Can also be used in a simple manual mode – just select your effect and tweak it by adjusting the parameter knobs in real time
  • Up and Down patch change footswitches and True bypass footswitch
  • Advanced low-noise 4-FET preamplifier designed to emulate the valve preamplifiers used in some of the classic tape echo machines
  • Gain and Pre Level knobs control the generation of ‘valve-like’ harmonics and match a wide range of guitar pickups from vintage single coils to ‘hot’ humbuckers
  • Master output level control to match the bypass level or maybe set it for a clean boost with a ‘No Effect’ patch
  • Fully-featured Patch Editor & Librarian application which is Free to download.

Some links to the Blue Nebula User Manual, the Building Instructions and the Bill of Materials are given below.

If you are thinking of building a Blue Nebula please read the Building Instructions thoroughly to determine if it is within your capabilities. Most of the components are through-hole types but there are a few surface mount components. The kit can be supplied with these already soldered in place for you.

Blue Nebula User Manual

Blue Nebula Building Instructions

Blue Nebula Bill of Materials